Biology 0610 · IGCSE · Gas exchange in humans

Gas exchange in humans — practice question

What makes air move into the lungs?

  • Aexternal intercostal muscles contract; volume of thorax decreases; air pressure in thorax decreases
  • Bexternal intercostal muscles relax; volume of thorax decreases; air pressure in thorax increases
  • Cexternal intercostal muscles contract; volume of thorax increases; air pressure in thorax decreases
  • Dexternal intercostal muscles relax; volume of thorax increases; air pressure in thorax increases

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